When stick-type products are placed into their respective cases they are held in place with a holder cup. The means by which the stick-type product is held in the cup is via a friction fit between the stick-type product and the inner wall of the holder cup. These two elements, the holder cup and the stick product, are dimensioned so that a proper friction fit is obtained. The problem with this means of holding the stick-type product in the holder cup is that, over time, the dimensions of the stick-type product will change, thereby causing the friction fit between the cup and the product to be insufficient to hold the product in place during a shock to the case. The dimensions of stick-type products change due to the method of cooling of the product after molding or filling into the holder cup whereby the cooling causes product to shrink.
Also, with the increasing use of volatile ingredients within the formulations for stick-type products, shrinkage problems are a concern. These volatile ingredients tend to evaporate, which then causes the product to shrink. When this happens, a once proper fit between the holder cup and the product will no longer be sufficient to hold the product in place. Once shrinkage has occurred to the point where the fit between the holder cup and the product is insufficient to hold the product in place, a small shock to the case will cause the product to release. Once the product has released from the holder cup it is virtually useless to the consumer.
Current holder cups try to remedy this problem in a number of different ways. Some cups provide a holder wall which protrudes from the bottom of the holder cup, so that when the stick-type product is inserted into the holder cup a greater surface area of contact between the product and the holder cup is provided (see German Patent No. 3319031). Along the same premise of increasing the contact surface area, longitudinally extending internal ribs are added to the holder cup as disclosed in U.S. Pat. No. 3,175,680 to Fuglsang-Madsen et al. and U.S. Pat. No. 4,579,134 to Moore. U.S. Pat. No. 4,820,070, provides that the longitudinally extending internal ribs be a dove-tail design to further provide greater contact area and to hold the stick in place after shrinkage of the stick has occurred.
With the new formulations of stick products that contain a considerable amount of volatile ingredients, it has been found that the frictional forces created by these configurations of holder cups is not sufficient to hold the product in place after shrinkage of the stick has occurred and then the case experiences a shock. This insufficient frictional force is created after the stick shrinks because holder cups of the longitudinal rib style pre-form a groove within the stick product when the stick is inserted into the holder cup. The product then shrinks away from the pre-formed groove thereby lessening the contact surface and the frictional forces.
WO Patent No. 96/32031 to Bennett provides for a holder cup that employs the use of a spike which penetrates a lipstick to hold the lipstick in place. This spike is either attached to a snap-ring or an arm. Both embodiments allow the spike to pass through an aperture in the holder cup, thereby puncturing a lipstick. This type of holder cup is effective in holding a stick product in place after shrinkage because a groove is not formed when the product is inserted into the holder cup. Though effective in holding a lipstick in place within a holder cup, these embodiments require additional assembly or may be difficult to manufacture via known holder cup molding techniques.
U.S. Pat. No. 5,560,727 to Vaupel, discloses the use of spring elements provided on the lipstick holder to aid in holding the lipstick mass in place. These spring elements are pressed into the lipstick as the lipstick holder is retracted into the case and form rear-engaging lugs. The disadvantage to this arrangement is that the rear-engaging lugs do not lock in place after they are pressed into the lipstick.
The purpose of the present invention is to provide a holder cup which will secure a stick-type product in place when the case is exposed to a shock.
Another purpose of the present invention is to provide a holder cup that is simple to manufacture.
Another purpose of this invention is to provide a holder cup which will continue to hold a stick-type product in place even after the product changes its dimensions.
Further, it is a purpose of this invention to provide a holder cup which can be used with existing case components with little or no modification to the case.
It is still a further purpose of this invention to provide a holder cup which is a relatively simple device that avoids interference with package aesthetics.